docs(uix sidebar): list LinkPreview, Menubar, Command under Overlays

The 3 newly-ported components (commits 0afcabee, 9def877d, 8ab8f9da)
were accessible by direct URL but missing from the sidebar nav in
\`web/routes/uix/+layout@.svelte\` (it's a hardcoded slug list, not
auto-discovered).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

web/routes/uix/+layout@.svelte

@@ -201,6 +201,9 @@
 				{ slug: '/uix/components/popover', label: 'Popover' },
 				{ slug: '/uix/components/dropdown-menu', label: 'Dropdown menu' },
 				{ slug: '/uix/components/context-menu', label: 'Context menu' },
+				{ slug: '/uix/components/menubar', label: 'Menubar' },
+				{ slug: '/uix/components/command', label: 'Command' },
+				{ slug: '/uix/components/link-preview', label: 'Link preview' },
 				{ slug: '/uix/components/toast', label: 'Toast' },
 				{ slug: '/uix/components/tooltip', label: 'Tooltip' }
 			]